Engineered
TAL Effector Technology

Welcome to TALengineering.org, a comprehensive resource of information
and resources for practicing engineered TAL (Transcription Activator-Like)
effector technology. This website, created and maintained by the
Joung Lab
at the Massachusetts
General Hospital, will strive to provide a one-stop
location for those interested in constructing TAL effector proteins
with customized DNA-binding specificities.

Naturally occurring TAL effectors harbor highly conserved repeat
domains that each bind to a single base pair of DNA. The identities
of two residues (referred to as repeat variable di-residues or
RVDs) in these 33 to 35 amino acid repeats are associated with
the binding specificity of these domains. Recent work from multiple
labs has shown that these repeats can be joined together to
create extended arrays capable of binding to target DNA sequences
of interest. Efficient DNA-binding by TAL effector repeat arrays
also requires the presence of additional N-terminal and C-terminal
amino acid sequences derived from naturally occurring TAL effectors.
Over the past several years, a variety of different assembly
platforms have been developed that enable interested researchers
to assemble DNA encoding customized TAL effector repeat arrays.

Engineered TAL repeat arrays can be fused to functional domains
to create artificial proteins with novel functions. Fusion of
TAL effector repeat arrays to the non-specific FokI nuclease domain
has resulted in the production of customizable endonucleases known
as TAL effector nucleases (TALENs). Repair of double-strand DNA
breaks induced by TALENs can be exploited to induce targeted insertion/deletion
mutations (by non-homologous end-joining-mediated repair) or specific
substitutions or insertions (by homology-directed repair). TAL
effector repeat arrays have also been fused to transcriptional
regulatory domains to create artificial transcription factors.

We hope that the information provided on this webpage will be
helpful to those interested in making their own customized TAL
repeat arrays. We also welcome suggestions for additional materials
about TAL effector technology not yet listed on these pages.